When constructing new digital radio communication systems, there is a need for increasing data rates in the system in relation to data rates of preceding radio communication systems to satisfy service demand. New services are continuously provided, which require higher data rates. To support higher data rates, e.g., Long Term Evolution Advanced (LTE-Advanced) is being developed. Also, in order not to force users of the preceding radio communication system to buy new equipment, such as user equipment devices (UEs), every time a new radio communication system or an updated version of an old system is launched, backwards compatibility should preferably be assured in the new or updated radio communication system. This gradual change of equipment requirements also gives the users some time to exchange their equipment.
In this document, the embodiments of the disclosure will be exemplified for the LTE-Advanced system, and thus for Advanced E-UTRA. However, the embodiments of the disclosure are applicable to essentially any system utilizing multicarrier transmission, such as Orthogonal Frequency Division Multiplexing (OFDM) transmission, as is clear for a skilled person. The term LTE is generally used for denoting Evolved Universal Terrestrial Radio Access/Evolved Universal Terrestrial Radio Access Network (E-UTRA/E-UTRAN). Correspondingly, the term LTE-Advanced is in this document used for denoting Advanced E-UTRA/Advanced E-UTRAN, and eNodeB denoting a base station of such system.
For the LTE/LTE-Advanced case, backwards compatibility means that a LTE User Equipment (UE) should be able to work in the LTE-Advanced system. Correspondingly, here, and throughout this document, “backwards compatible” (or simply “compatible”) means that equipment of a legacy system (i.e. an older system) should be able to work in the new system being defined.